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Adrenergic Agents and Adrenergic Blocking-Agents

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									         Drugs Affecting The
      Autonomic Nervous System
                      Adrenergic Agents and
                    Adrenergic-Blocking Agents



Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
         Instructors may choose to insert
                  EIC Image #48:

      The Sympathetic Nervous System
        in Relationship to the Entire
              Nervous System

Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents

  • Drugs that stimulate the sympathetic nervous
    system (SNS)




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents

  Also known as
  • adrenergic agonists or sympathomimetics




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents

  Mimic the effects of the SNS neurotransmitters:
  • norepinephrine (NE) and epinephrine (EPI)




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Receptors

  • Located throughout the body
  • Are receptors for the sympathetic
    neurotransmitters
      Alpha-adrenergic receptors: respond to NE
        Beta-adrenergic receptors: respond to EPI




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Alpha-Adrenergic Receptors

  • Divided into alpha1 and alpha2 receptors
  • Differentiated by their location on nerves




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Alpha1-Adrenergic Receptors

  • Located on postsynaptic effector cells
    (the cell, muscle, or organ that the nerve
    stimulates)




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Alpha2-Adrenergic Receptors

  • Located on presynaptic nerve terminals
    (the nerve that stimulates the effector cells)
  • Control the release of neurotransmitters




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 The predominant alpha-adrenergic
 agonist responses are:
  • Vasoconstriction and CNS stimulation




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Beta-Adrenergic Receptors

  All are located on postsynaptic effector cells
  • Beta1-adrenergic receptors—located primarily
    in the heart
  • Beta2-adrenergic receptors—located in smooth
    muscle of the bronchioles, arterioles, and visceral
    organs




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 The beta-adrenergic agonist
 response results in:
  • Bronchial, GI, and uterine smooth muscle
    relaxation
  • Glycogenolysis
  • Cardiac stimulation




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Dopaminergic Receptors
  • An additional adrenergic receptor
  • Stimulated by dopamine
  • Causes dilation of the following blood
    vessels, resulting in INCREASED blood flow
        – Renal
        – Mesenteric
        – Coronary
        – Cerebral
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Receptor Responses
 to Stimulation
  LOCATION                              RECEPTOR                       RESPONSE
  Cardiovascular
  Blood vessels                         alpha1 and beta2               Constriction /
                                                                       dilation
  Cardiac muscle                        beta1                          Increased
                                                                       contractility
  AV Node                               beta1                          Increased
                                                                       heart rate
  SA Node                               beta1                          Increased
                                                                       heart rate
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Receptor Responses
 to Stimulation
  LOCATION                              RECEPTOR                       RESPONSE
  Gastrointestinal
  Muscle                                beta2                          Decreased
                                                                       motility
  Sphincters                            alpha1                         Constriction




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Receptor Responses
 to Stimulation
  LOCATION                              RECEPTOR                       RESPONSE
  Genitourinary
  Bladder                               alpha1                         Constriction
  sphincter
  Penis                                 alpha1                         Ejaculation
  Uterus                                alpha1 and beta2               Contraction/
                                                                       relaxation




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Receptor Responses
 to Stimulation
  LOCATION                            RECEPTOR                         RESPONSE
  Respiratory
  Bronchial                           beta2                            Dilation/relaxation
  muscles




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Catecholamines

  Substances that can produce a sympathomimetic
   response
  Endogenous:
  • epinephrine, norepinephrine,dopamine


  Synthetic:
  • isoproterenol, dobutamine, phenylephrine


Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents
 Mechanism of Action
  Direct-acting sympathomimetic:
  • Binds directly to the receptor and causes a
    physiologic response




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        Direct-Acting Sympathomimetics




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents
 Mechanism of Action
  Indirect-acting sympathomimetic:
  • Causes the release of catecholamine from the
    storage sites (vesicles) in the nerve endings
  • The catecholamine then binds to the receptors and
    causes a physiologic response




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
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      Indirect-Acting Sympathomimetics




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents
 Mechanism of Action
  Mixed-acting sympathomimetic:
  • Directly stimulates the receptor by binding
    to it
      AND
  • Indirectly stimulates the receptor by causing
    the release of stored neurotransmitters from
    the vesicles in the nerve endings




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
         Instructors may choose to insert
                  EIC Image #54:

        Mixed-Acting Sympathomimetics




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Drug Effects of Adrenergic Agents
  Stimulation of alpha-adrenergic receptors on
    smooth muscles results in:
  • Vasoconstriction of blood vessels
  • Relaxation of GI smooth muscles
  • Contraction of the uterus and bladder
  • Male ejaculation
  • Decreased insulin release
  • Contraction of the ciliary muscles of the eye
    (dilated pupils)
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Drug Effects of Adrenergic Agents

  Stimulation of beta2-adrenergic receptors on
    the airways results in:
  • Bronchodilation (relaxation of the bronchi)
  • Uterine relaxation
  • Glycogenolysis in the liver




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Drug Effects of Adrenergic Agents
  Stimulation of beta1-adrenergic receptors on
    the myocardium, AV node, and SA node
    results in CARDIAC STIMULATION:
  • Increased force of contraction
    (positive inotropic effect)
  • Increased heart rate
    (positive chronotropic effect)
  • Increased conduction through the AV node
    (positive dromotropic effect)


Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents:
 Therapeutic Uses
  • Anorexiants: adjuncts to diet in the
    short-term management of obesity
      Examples:                      benzphetamine
                                     phentermine
                                     dextroamphetamine
                                     Dexedrine




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents:
 Therapeutic Uses
  Bronchodilators: treatment of asthma and
   bronchitis
  • Agents that stimulate beta2-adrenergic receptors
    of bronchial smooth muscles causing relaxation
      Examples:
      albuterol                               ephedrine                epinephrine
      isoetharine                             isoproterenol            levalbuterol
      metaproterenol                          salmeterol               terbutaline
  • These agents may also affect uterine and vascular
    smooth muscles.
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents:
 Therapeutic Uses
  • Reduction of intraocular pressure and
    mydriasis (pupil dilation): treatment of
    open-angle glaucoma
      Examples:                    epinephrine and dipivefrin




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents:
 Therapeutic Uses
  Nasal decongestant:
  • Intranasal (topical) application causes constriction
    of dilated arterioles and reduction of nasal blood
    flow, thus decreasing congestion.
      Examples:
      epinephrine                           ephedrine                  naphazoline
                                            phenylephrine
                                            tetrahydrozoline



Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents:
 Therapeutic Uses
  Ophthalmic
  • Topical application to the eye surface affects
    the vasculature of the eye, stimulating alpha
    receptors on small arterioles, thus relieving
    conjunctival congestion.
      Examples:                   epinephrine                          naphazoline
                                  phenylephrine                        tetrahydrozoline




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents:
 Therapeutic Uses
  Vasoactive sympathomimetics (pressors,
   inotropes), also called cardioselective
   sympathomimetics
  • Used to support the heart during cardiac failure
    or shock.
      Examples:
      dobutamine                        dopamine                       ephedrine
      epinephrine                       fenoldopam                     isoproterenol
                                        methoxamine                    norepinephrine
                                        phenylephrine
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents: Side Effects
  Alpha-Adrenergic Effects
  • CNS:
     – headache, restlessness, excitement, insomnia,
       euphoria

  • Cardiovascular:
     – palpitations (dysrhythmias), tachycardia,
       vasoconstriction, hypertension

  • Other:
     – anorexia, dry mouth, nausea, vomiting, taste
       changes (rare)
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents: Side Effects
  Beta-Adrenergic Effects
  • CNS:
        – mild tremors, headache, nervousness, dizziness


  • Cardiovascular:
        – increased heart rate, palpitations (dysrhythmias),
          fluctuations in BP


  • Other:
        – sweating, nausea, vomiting, muscle cramps

Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents: Interactions
  • Anesthetic agents
  • Tricyclic antidepressants
  • MAOIs
  • Antihistamines
  • Thyroid preparations
  • Antihypertensives
  • Will directly antagonize another adrenergic
    agent, resulting in reduced effects
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents:
 Nursing Implications
  • Assess for allergies and history of
    hypertension, cardiac dysrhythmias, or other
    cardiovascular disease.
  • Assess renal, hepatic, and cardiac function
    before treatment.
  • Perform baseline assessment of vital signs,
    peripheral pulses, skin color, temperature,
    and capillary refill. Include postural blood
    pressure and pulse.
  • Follow administration guidelines carefully.
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents:
 Nursing Implications
  IV administration:
  • Check IV site often for infiltration
  • Use clear IV solutions
  • Use an infusion device/IV pump
  • Infuse agent slowly to avoid dangerous
    cardiovascular effects
  • Monitor cardiac rhythm


Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents:
 Nursing Implications
  With chronic lung disease:
  • Instruct patients to avoid factors that exacerbate
    their condition.
  • Encourage fluid intake
    (up to 3000 mL per day) if permitted.
  • Educate about proper dosing and
    equipment care.

                Salmeterol is indicated for PREVENTION
                   of bronchospasms, not management
                            of acute symptoms.
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents:
 Nursing Implications
  • Overuse of nasal decongestants may cause rebound
    nasal congestion or ulcerations.
  • Avoid OTC or other medications because of possible
    interactions.
  • Administering two adrenergic agents together may
    precipitate severe cardiovascular effects such as
    tachycardia or hypertension.
  • Inform patients taking inhaled isoproterenol that
    their sputum or saliva may turn pink.


Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents:
 Nursing Implications
  Monitor for therapeutic effects
   (cardiovascular uses):
  • Decreased edema
  • Increased urinary output
  • Return to normal vital signs
  • Improved skin color and temperature
  • Increased LOC


Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Agents:
 Nursing Implications
  Monitor for therapeutic effects (asthma):
  • Return to normal respiratory rate
  • Improved breath sounds, fewer rales
  • Increased air exchange
  • Decreased cough
  • Less dyspnea
  • Improved blood gases
  • Increased activity tolerance
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic-Blocking Agents

  • Bind to adrenergic receptors, but inhibit or
    block stimulation of the sympathetic nervous
    system (SNS)




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Blocking Agents

  • Have the opposite effect of adrenergic
    agents
  • Also known as
        – adrenergic antagonists or sympatholytics




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Blocking Agents

  • Sympatholytics inhibit—or LYSE—
    sympathetic neurotransmitters

      (norepinephrine and epinephrine)




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Blocking Agents

  Classified by the type of adrenergic receptor
   they block
  • Alpha1 and alpha2 receptors
  • Beta1 and beta2 receptors




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                 EIC Image #55:

                Alpha-Blocker Mechanisms




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic-Blocking Agents:
 Drug Effects and Therapeutic Uses
  Ergot Alkaloids (Alpha-Blockers)
  • Constrict dilated arteries going to the brain
    (carotid arteries)
  • Used to treat vascular headaches (migraines)
  • Stimulate uterine contractions by inducing
    vasoconstriction
  • Used to control postpartum bleeding



Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic-Blocking Agents:
 Drug Effects and Therapeutic Uses
  Alpha-Blockers
  • Cause both arterial and venous dilation, reducing
    peripheral vascular resistance and BP
  • Used to treat hypertension
  • Effect on receptors on prostate gland and bladder
    decreased resistance to urinary outflow, thus
    reducing urinary obstruction and relieving effects
    of BPH



Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic-Blocking Agents:
 Drug Effects and Therapeutic Uses
  Alpha-Blockers
  • Phentolamine
        – Quickly reverses the potent vasoconstrictive effects of
          extravasated vasopressors such as norepinephrine or
          epinephrine.
        – Restores blood flow and prevents tissue necrosis.




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic-Blocking Agents:
 Side Effects
  Alpha Blockers
  Body System                              Side/Adverse Effects
  Cardiovascular                           Palpitations, orthostatic
                                           hypotension, tachycardia,
                                           edema, dysrhythmias, chest pain

  CNS                                      Dizziness, headache, drowsiness,
                                           anxiety, depression, vertigo,
                                           weakness, numbness, fatigue

Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic-Blocking Agents:
 Side Effects
  Alpha Blockers
  Body System                              Side/Adverse Effects
  Gastrointestinal                         Nausea, vomiting, diarrhea,
                                           constipation, abdominal pain

  Other                                    Incontinence, nose bleeding,
                                           tinnitus, dry mouth, pharyngitis,
                                           rhinitis


Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Beta Blockers

  • Block stimulation of beta receptors in
    the SNS
  • Compete with norepinephrine and
    epinephrine
  • Selective and nonselective beta blockers




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Beta Receptors

  Beta1 Receptors
  • Located primarily on the heart
  • Beta blockers selective for these receptors
    are called cardioselective beta blockers




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Beta Receptors

  Beta2 Receptors
  • Located primarily on smooth muscles
    of bronchioles and blood vessels




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Nonspecific Beta Blockers

  • Beta blockers that block both beta1 and
    beta2 receptors




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Beta Blockers: Mechanism of Action

  Cardioselective (Beta1)
  • Decreases heart rate
  • Prolongs SA node recovery
  • Slows conduction rate through the AV node
  • Decreases myocardial contractility, thus
    decreasing myocardial oxygen demand




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Beta Blockers: Mechanism of Action

  Nonspecific (Beta1 and Beta2)
  • Effects on heart:                            Same as cardioselective
  • Bronchioles:                                 Constriction, resulting in
                                                 narrowing of airways and
                                                 shortness of breath
  • Blood vessels:                               Vasoconstriction




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Beta Blockers: Therapeutic Uses

  • Anti-angina:                                          decreases demand for
                                                          myocardial oxygen
  • Cardioprotective:                                     inhibits stimulation by
                                                          circulating catecholamines

  • Class II antidysrhythmic




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Beta Blockers: Therapeutic Uses

  • Antihypertensive
  • Treatment of migraine headaches
  • Glaucoma (topical use)




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Beta Blockers: Side Effects

  Body System                            Side/Adverse Effects
  Blood                                  Agranulocytosis, thrombocytopenia

  Cardiovascular                         AV block, bradycardia, congestive
                                         heart failure, peripheral vascular
                                         insufficiency

  CNS                                    Dizziness, mental depression,
                                         lethargy, hallucinations

Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic-Blocking Agents:
 Side Effects
  Beta Blockers
  Body System                                Side/Adverse Effects
  Gastrointestinal                           Nausea, dry mouth, vomiting,
                                             diarrhea, cramps, ischemic colitis


  Other                                      Impotence, rash, alopecia,
                                             bronchospasms



Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Blocking Agents:
 Nursing Implications
  • Assess for allergies and history of COPD,
    hypotension, cardiac dysrhythmias,
    bradycardia, CHF, or other cardiovascular
    problems

                  Any preexisting condition that might be
               exacerbated by the use of these agents might
                 be a CONTRAINDICATION to their use.



Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Blocking Agents:
 Nursing Implications
  • Remember that alpha blockers may
    precipitate hypotension.
  • Remember that beta blockers may
    precipitate bradycardia, hypotension,
    heart block, CHF, and bronchoconstriction.




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Blocking Agents:
 Nursing Implications
  • Avoid OTC medications because of possible
    interactions.
  • Possible drug interactions may occur with:
        – Antacids (aluminum hydroxide type)
        – Antimuscarinics/anticholinergics
        – Diuretics and cardiovascular drugs
        – Neuromuscular blocking agents
        – Oral hypoglycemic agents
Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Blocking Agents:
 Nursing Implications
  • Encourage patients to take medications
    as prescribed.
  • These medications should never be
    stopped abruptly.
  • Report constipation or the development of
    any urinary hesitancy or bladder distention.




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Blocking Agents:
 Nursing Implications
  • Teach patients to change positions slowly to
    prevent or minimize postural hypotension.
  • Avoid caffeine (excessive irritability).
  • Avoid alcohol ingestion and hazardous
    activities until blood levels become stable.
  • Patients should notify their physician if
    palpitations, dyspnea, nausea, or vomiting
    occur.

Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Beta Blocking Agents:
 Nursing Implications
  • Rebound hypertension or chest pain may occur if
    this medication is discontinued abruptly.
  • Patients should notify their physician if they become
    ill and unable to take medication.
  • Inform patients that they may notice a decrease in
    their tolerance for exercise; dizziness and fainting
    may occur with increased activity. Notify the
    physician if these problems occur.



Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Beta Blocking Agents:
 Nursing Implications
  Patients should report the following to
   their physician:
  • Weight gain of more than 2 pounds (1 kg)
    within a week
  • Edema of the feet or ankles
  • Shortness of breath
  • Excessive fatigue or weakness
  • Syncope or dizziness

Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Blocking Agents:
 Nursing Implications
  Monitor for side effects, including:
  Hypotension                                                          Fatigue
  Tachycardia (alpha blockers)                                         Lethargy
  Bradycardia                                                          Depression
  Heart block                                                          Insomnia
  CHF                                                                  Vivid nightmares

  Increased airway resistance

Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
 Adrenergic Blocking Agents:
 Nursing Implications
  Monitor for therapeutic effects
  • Decreased chest pain in patients with angina
  • Return to normal BP and P
  • Other specific effects, depending on the use




Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.

								
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